Tool sharpening apparatus



Aug. 30, 1938. l l w. H. MCGILL 2,128,591 TOOL SHARPENING PPARATUS Filed Jan. 5', 1936" r /N VENTO Patented Aug. 30, 1938 l AUNITED STATES PATENT O-FFQIQE .TOOL SHARPENING APPARATUS William H. .McGill, Winchester,.Mass. :Application January 3, 1936, Serial No. 57,375 solaims. (o1. 51-158) This invention relates to apparatus for facilia guiding plate 5. Preferably .this plate is made tating. the hand sharpening of -edged tools, such of hardened steel, although this is not always as. chisels, gouges, blades, and others: ofthe type necessary. When the apparatus is in use the in which it is importantto have the edge ground plate is stationary, but it is mounted for Vertior sharpened to a uniform or .other predetercal adjustment relatively to the stone, this 5 mined bevel. mounting comprising a cup-shaped member 6,

Various devices designed to accomplish this ob- V of relatively short Vertical dimensions, but .project have been proposed heretofore but those of vided with a screw threaded shank 1 supported in which I have been able to learn have been of an internally threaded bushing .8 withv which such a nature as torestrict or hamper the movethe ibase 2 is equipped. By fitting the threads 10 ments required in performing certain of 'these tightly suicient friction is provided between hand sharpening operations. Such movements these parts to hold the plate against accidental includenot only free movements of the tool'over change of adjustment, while still Y'permitting the the stone while its edge is held .in contact vwith part 6 :to be revolved to raise or lower it. l5 the grinding surface, .but also freedom to pick Assuming that the tool to be sharpened is a 15 up the tool at any instantto examine itsedge. hand plane blade IU, such a blade is mounted To devise an apparatus of lthegeneralfcharin .a holder I2 comprising a yoke-shaped body acter above designated which=will 'avoid the obmember provided with a slot throughwhich the jections just described, constitutesthe` chief obblade may be slipped freely, and a clamping ject of the present invention. screw I3 threaded through the upper arm ofthe 20 The nature of the invention willbe readily yoke and-provided above said arm with athumb understood from the'followingdescription when piece lll land below it with a foot l5 .adapted to read in connection with the accompanying-drawbear on the shank portion of the blade or other ing, and the novel features V.will be particularly tool l0. .By tipping the tool and the yoke, one mi pointed out inthe appended claims. relatively to the other,untl the two edges of In the drawing, theblade l0 are in contact withthe opposite ver-v Figure l is a perspectiveview, 4with some parts tical arms of the yoke, the blade will'be `centered broken away,ofan apparatus constructed in facin the holder. Then by turning downthe screw cordance with this invention; I4 the blade can be securely clamped against the 3o Fig. 2 is a plan View of i' the apparatusillusbase piece of the holder. 30 trated in Fig. 1; Projecting from the lower side of the yoke l2 Fig. 3 is a vertical, sectional View through a is .an .arm t6, .rigid with the `part |12, and havportion of the base and the guide plate mounted ing a ball I'lmounted in its lower extremity. The thereon, showing the DIOViSOIl fOr adjustment walls of the socket inwhich the ball is supported :l5 of the latter relatively to the base; are so crimped overthat they retain the ball ef- 35 Fig. 4 is a sectional View through the tool fectively, while at the same time permitting the holder; and ball to revolve freely around its own center.

Fig. '5 is a lfront` elevation of a diierent 'form When the blade'has been secured in the holder,

of holder designed for use in -sharpening gouges. as above described, the assembly is positioned .lo Referring flI'S t0 Figs. 1 and-2,' the apparatus as illustrated in Figs. 1 and 2 with the beveled 40 there shown comprises abaSe 2 Whiehmey C011- edge of the blade resting on the upper surface ifeniently be made 0f castfiron 0.1. any other Suitof the stone a and the bau a1 riding on the non able material. In the upper Side Of-'hS base a zontal surface of the plate 5. The .workman then socket 3 is provided to IeCeiVe La gl'ldStOIle 01 moves the blade over the .surface ofthe stone,V

u equivalent Sharpening deVCel FOI many Pulexactly as'hewould in hand sharpening without 45 poses it is desirable to use la circular stone, as the aid 0f any guiding device. such movements ShOWl, and 'G0 have-011e Side 0f the :SOne 0f a usually include a somewhat circular motion of Coarse, fast-Cutting material, While the Opposite the blade on the stone, the edge of the tool beside is of a much finer-grained and slower cut-v ing moved over practically the entire face of the m'- ting composition. `-For this purpose -the socketv stone as the sharpening operation progresses so 50 31preferably is :made l.somewhat larger inv diamthat the vstone will .be kept level and localized eter than the stonefsok thatfthe latter 'can conwear will be substantially avoided. During all veniently be 'lifted out Vof .,it, freversed and -reof these movements the -angle of the blade due placed. f the stone remains constant and unvarying due mi At one Side of thestone'A-.thebase y2 supports to the fact that this angle is determined :by the 55 distance between the blade and the surface of the ball I1 at its point of contact With the plate 5. This distance remains constant notwithstanding the movement of the blade over the stone. Thus the workman is relieved of the difcult operation of maintaining the blade continuously at the same angle, which is absolutely essential in order to grind the edge to a uniform bevel.

Adjustment of the angle of the tool on the face of the stone 4 can be made by changing the relative elevation of the stone and the guiding plate 5, or the length of the arm I6. Preferably, however, this is accomplished by the screw mounting of the plate, as above described, and as shown in Fig. 3. It will readily be observed that if the plate is revolved toward the right, Fig. l, it will be lowered, thus tending to grind the heel of the bevel more rapidly, whereas if the plate is revolved in the opposite direction the blade will be tipped up so that more of the grinding operation Will be conned to the extreme edge of the blade.

Attention is directed to the fact that the only contact between the holder and the guide plate 5 is one of surface engagement, the ball moving freely over the upper surface of the plate in any direction as the sharpening operation progresses. This is important for the reason that as said operation proceeds, thevworkman lifts the blade Ill from time to time and examines its edge to see whether or not the bevel is correct, and whether the edge is sharp enough. Toward the completion of this operation he will test the edge on his thumb, or in any other way to which he is accustomed. If he finds that the bevel is not right, he will make suitable adjustment to correct the difficulty. If the edge is still dull he will continue with the sharpening operation until finally he has produced the condition which he desires. However, the fact that he can lift the blade off the stone at any time and handle it exactly as he would if the holder were not on it, and replace it again instantly without disturbing any adjustment, is an important practical advantage. In other words, this apparatus requires no change in the hand sharpening practice or method but it gives the workman the advantage of maintaining the correctl bevel constantly without effort on his part. At the same time the workman can perform the sharpening operation more rapidly, both because of maintaining the exact bevel continuously and also for the reason that greater power and pressure can be applied, especially in the roughing operation.

In order to prevent the lower ball end of the guide member I 6 from running ofi" the edge of the guide plate 5, the holder in which this plate is mounted preferably is provided with an upright arm or margin I8, closely surrounding the plate and projecting above it. The outer cylindrical surface of this member may be knurled, as shown in Fig. 1, in order to facilitate the rotation of this holder in making the adjustment above described.

When the sharpening operation has been completed the screw I3 is backed up, thus releasing the blade Il) and permitting the workman to withdraw it from the holder. When-ever a blade is inserted and centered in the manner above described, the greater part, if not all, of this lcentering operation will be performed automatically by the twisting of the blade in the holder as the clamping screw I3 is tightened up. This same operation centers the blade with reference to the guiding arm I 6.

Such a holder as that illustrated in Figs. 1, 2 and 4 can be used with a great variety of edged tools. Some tools, however, and some blades will require a special form of holder. One such form is illustrated at 2U in Fig, 5, this holder being designed for use in sharpening gouges. The shank of the gouge 2I is supported on the tapered walls of the body portion of the holder, and it is clamped against them by a screw 22. In sharpening a gouge, however, a transverse rocking movement of the tool on the stone is necessary in order to present different portions of the curved edge of the tool to the stone. At the same time the angular relationship of the tool to the stone should be maintained in order to produce a uniform bevel. This result may be conveniently accomplished by equipping the holder with a templet 23, the lower edge of which has the same transverse curvature as the gouge. The edge of this member can be both moved over the plate 5 in any direction and also rocked on this plate as the sharpening operation progresses, thus enabling Vthe Workman to grind the entire edge to the correct bevel but relieving him of the effort and skill required to hold the tool continuously in the correct angular relationship to the stone. The

yternplet 23 may consist of a thin plate inserted in a saw cut or slot in the holder and clamped securely, but removably, by a screw 24.

While I have herein shown and described a typical embodiment of my invention, it will be evidentthat the invention may be embodied in other forms without departing from the spirit or scope thereof. k

Having thus described my invention, what I desire to claim as new is:

1. In a tool sharpening apparatus, the combination of a flat, relatively stationary grindstone, a tool holder comprising a yoke-shaped body member, a base piece connecting the arms of said member, a screw carried by said yoke for engagement withthe base piece to clamp the tool securely butv releasably in the holder for the sharpening operation, a guide plate, a support for holding said stone and said plate positioned horizontally and closely adjacent to each other, said tool holder including an arm rigid therewith and in axial alinement with said screw and having a round ended guiding member at its lower end arranged to bear on the upper face of said plate and freely movable in any direction on said face, said member cooperating with said plate and said holder to determine the angle at which said tool will be held on the surface of said stone while the tool is moved over the stone, and means for preventing the movement of said guiding member off the edge of the plate.

2. In a tool sharpening apparatus, the combination of a flat, relatively stationary grindstone, a base having a socket therein to receive said stone and to support the same in a horizontal position, said socket and stone being constructed to permit the angular adjustment of the stone into a series of different positions therein whereby the wear on the stone may be distributed more uniformly, a horizontal guide plate mounted on said base closely adjacent to said stone, a tool holder constructed to clamp the tool to be sharpened securely but releasably therein for the sharpening operation, said tool holder including a guiding member arranged to bear on the upper face of said plate and freely movable in any direction on said face, said member cooperating with said plate and said holder to determine the angle at which said tool will be held nation of a flat, relatively stationary grindstone of circular outline, a base having a circular socket therein to receive said stone and to support the same horizontally for rotative adjustment in said socket, a tool holder constructed to clamp the tool to be sharpened securely but releasably therein for the sharpening operation, a horizontal guide plate mounted on said base adjacent to said socket, said tool holder includingV a guiding member arranged to bear on the upper face of said plate and freely movable in any direction on said face, said member cooperating with said plate and said holder to determine the angle at which said tool will be held on the surface of said stone while the tool is moved over the stone, and means adjustable to change the angular relationship of said tool to the grinding face of said stone.

4. In a tool sharpening apparatus of the character described, a grindstone, a guide plate, a support for the stone and plate, a yoke-shaped tool holder having a slot therethrough for the reception of the shank of the tool, said slot having end and bottom walls and being wider than said shank and permitting lateral movement of the shank in the holder, said movement being limited by the end walls of said slot, a clamping screw threaded through the upper wall of the yokeshaped portion of the holder for exerting pressure on said tool perpendicular to said plane of lateral movement to clamp said tool in said slot against said lower Wall, an arm rigid with said yoke-shaped portion and extending therefrom in axial alinement with said screw, and said arm having an end face curved about a center lying in said axis and adapted to bear on said guide plate. ,l

5. In a tool sharpening apparatus, the combination of a flat, relatively stationary grindstone, a base having a socket therein to receive said stone and to support the same in a horizontal plane, said socket and stone being constructed to permit the angular adjustment of the stone in said horizontal plane into a seriesy of different positions therein whereby the wear on the stone may be distributed more uniformly, a horizontal guide plate over which the tool is guided during the sharpening thereof mounted on said base closely adjacent to said stone, screw threaded means supporting said plate for adjustment vertically relatively to said stone, and a tool holder provided with a guide arm adapted to rest upon and move freely over the surface of the guide plate.

WILLIAM H. MCGILL. 

